Prefabricated insulated exterior wall panels are designed to span multiple floors of a building, and are being constructed to withstand thermal changes (e.g. temperature-related expansion and contraction), moisture and condensation buildup, wind and other forces, while at the same time keeping air and water from penetrating the building envelope and contributing to a decorative appearance. Due to new Leadership in Energy and Environmental Design (“LEED”) standards, current insulated panels, such as curtain wall “backpanels” or external aluminum composite panels (ACPs), are necessarily being constructed to provide thermal efficiency (i.e. high heat transfer coefficient) for cost-effective heating, cooling and lighting in a building, while contributing to a decorative and aesthetically pleasing exterior appearance.
Aluminum Composite Panels (ACPs) are commonly used as external wall panels in building construction for external cladding (building facades), for insulation and/or for signage. Existing ACPs typically comprise a non-aluminum internal core bonded with one aluminum sheet, or sandwiched between two sheets, depending upon the type and style of panel. For instance, ACPs may comprise two external aluminum sheets, or “skins”, that are adhered together by an internal insulating core. Where two sheets are utilized, a thermal plastic core such as, for example, a polyethylene (PE) or other polymer foam material (e.g. expanded polyurethane or expanded resin) may be used. Various forms of ACPs are known including, without limitation, Reynobond® panels, Alucobond® panels and Alpolic® panels.
Curtain walls can comprise a non-structural exterior covering of a building, and are typically constructed with extruded aluminum or steel members. The metal frame of the curtain wall is typically non-load bearing and can house glass or other opaque decorative coverings that are used in combination with internal, insulated “backpanels”, known as “curtain wall panels”.
Although not apparent from the exterior of the building, the backpanels in a curtain wall system often comprise considerable insulation. The backpanels are not only designed to withstand thermal changes, moisture and condensation, wind and other forces, while at the same time keeping air and water from penetrating the building envelope, but they are also designed to maintain pressure and temperature consistency in the intentional gap formed between the backpanel and the decorative opaque covering.
Unlike ACPs, insulated curtain wall backpanels may comprise formed sheet(s) of steel or aluminum and a cavity or “back-section” filled with insulation. Traditionally, insulated backpanels may comprise rigid fiberglass or mineral wool insulation fastened inside a cavity formed from a single sheet of aluminum or steel. Alternatively, one form of insulated composite panel comprises two external aluminum or steel sheets having expanded insulating material sandwiched therebetween. For instance, as described in U.S. Pat. No. 3,530,029, composite panels may be formed by aligning equal lengths of sheet material, disposing a preformed insulating material therebetween and compressing the three layers in a press to form a length of panel. The insulating material may a polymer foam material (e.g. expanded polyurethane or other expanded resin) arranged between the two skins.
One common form of rigid wool insulation in traditional backpanels is Roxul CurtainRock®, which is a semi-rigid stone wool insulation board. Where rigid insulation is used, the aluminum or steel sheets are shaped to conform to sizes and shapes in compliance with the desired building design and then coated with a sealant to create a water and air barrier. Each formed cavity is then prepared to receive and secure expandable or rigid insulation. For example, “stickpins” can be installed to extend from the interior surface of the panel and are then coated with adhesive and used to hold the insulation in position.
The success of this insulation process depends upon the skill of the worker to adequately coat the pan and stickpins with the sealant and/or adhesive and then to pre-cut the insulation to the size of the backpan (i.e. to minimize gaps between the insulation and the backpan). Problems arise where the sealant is misapplied, resulting in air and water entering the backpan and causing the buildup of condensation. Further, thermal “shorts” or weaknesses often result where the insulation has not been installed properly and where it must part to allow the stickpins to puncture through the fibrous material. As a result, fluctuations in air pressure cause airflow through the gaps which can cause “whistling” noises. Heat buildup behind the insulation can also cause “drumming” noises due to vibration of the metal skin of the backpan and condensation buildup in the space between the insulation and the metal skin. Semi-rigid insulation can sag and weaken over time, causing the necessity for costly maintenance or repair. Finally, offcut insulation cannot be reused and creates waste.
Existing insulated ACPs and curtain wall panels also require additional attachment means such as, non-integrated extruded aluminum fasteners for installing the insulated panel to the building wall. The required attachment means complicates the installation process and requires that the panels conform to precise size and shape specifications. The complex panel attachment methods and the current types of insulation further restrict the ability to adapt or change the size and shape of the insulated panels on site, as may be required where building or architectural designs changes.
There exists a need for an efficient system of manufacturing insulated exterior wall panels and curtain wall backpans, each made from one piece of aluminum or steel and an effective and efficient form of insulation, thereby eliminating the need for both traditional curtain wall backpanel elements and complicated composite panel construction. There is further a need for a system of manufacturing insulated wall panels having integral attachment means. There is a need for a system capable of manufacturing lighter external wall panels and backpanels which are made of one piece of metal and insulated with a spray- or pour-foam insulation. The system may be entirely automated.